func homework() {
 group, errCtx :=errgroup.WithContext(context.Background())
 http.HandleFunc("/index", func(w http.ResponseWriter, r *http.Request) {

 })
 group.Go(func() error {
  err := http.ListenAndServe("127.0.0.1:8080", nil)
  if err != nil {
   return fmt.Errorf("..%v", 1)
  }
  return nil
 })
 group.Go(func() error {
  err := http.ListenAndServe("127.0.0.1:8000", nil)
  if err != nil {
   return fmt.Errorf("..%v", 2)
  }
  return nil
 })
 if err := group.Wait(); err != nil {
  fmt.Println(err)
 }

 select {
  case <- errCtx.Done():
   return
 default:
 }
 //TODO linux signal 待学习
}